Hot Briquetting of Direct Reduced - Maschinenfabrik KÃ¶ppern GmbH ...

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Hot briquetting of DRI closes internal pores, lowers the accessible surface, increases the apparent density, and improves thermal conductivity, all of which reduce reactivity (Fig. 1). Reoxidation and overheating of HBI is very unlikely. This results in considerable improvements of storage and transport characteristics. Additional advantages, such as higher density, improved handling, uniform product shape and size, as well as reduced fines production, are results of the physical characteristics of the HBI. DRI from fine ores, reduced in fluid bed processes, is even more reactive and, even after cooling, cannot be safely handled in the open. In this case, hot briquetting not only passivates the product but also solves the inherent handling problems associated with the fine particulate material. The reoxidation behaviour of HBI was tested in a production plant (MIDREX process) with a 600 t briquette pile [3]. Inspite of a tropical climate and high salt content in the atmosphere (coastal location) no heating occured and after open storage for one month only 0.8 % metallization was lost. Prior to the first transport by sea, tests were carried out using simulated ship holds where HBI was wetted with sea water. Again, the stability of the product was demonstrated [6]. Other trials evaluated the heating of briquetted material in an oxidizing atmosphere simulating the preheating of scrap. No loss of metallization was determined. The characteristics of HBI constitute important advantages as compared with the results of other passivation processes. For example the passivation effect of aging is much less pronounced and disappears in the presence of water, particularly seawater. For this reason, the advantages of HBI have become part of the IMO Shipping Regulation [4]. IMO distinguishes between DRI and "sponge iron which has been briquetted at temperatures of ≥ 650° C and has reached an apparent density of ≥ 5 g/cm³ (HBI). For the latter, in addition to considerably simplified shipping requirements, "open storage prior to loading" is acceptable. As compared with DRI, the following punch list provides a summary of the most important specific characteristics of HBI: - No change in the chemical analysis by the briquetting process. - Only minimal loss of metallization even after long time storage. - Open air storage both at the producer and user sites does not cause problems (no need for inertized silos as with DRI). - Minimum risk of overheating during storage and transport (e.g. IMO allows "open storage prior to loading"). - Special inertization of ship holds is not required (no specially equipped ships). - Little production of fines during handling. - Handling similar to scrap (open air storage, transport with front-end loaders, magnets, belts, redlers, etc.); an additional advantage is the relatively small and uniform product size (charging of furnaces). - High apparent and bulk densities. - Low moisture saturation (max. approx. 3 % as compared with 12-15 % for DRI [3]). - Efficient preheating for the EAF possible 3
For those reasons it is understandable that true merchant plants operating today are and most of the merchant facilities under construction or consideration will be producing HBI. In this context true merchant plants are defined as producers of prime, alternative iron units by direct reduction for the general, open world market where traders and users do not maintain special handling and inertized storage or shipping facilities. Producers utilizing specifically equipped ships or barges to supply a dedicated user that implemented extraordinary receiving, intermediate storage, and feeding systems are not considered true merchant plants. It should be mentioned that a lot of producers of DRI in integrated mini mills also operate briquetting systems. In these facilities a small amount of fines, that has been removed from the cold DRI by screening prior to feeding the EAF, is briquetted with a binder. Such briquettes have different uses in steel mills and foundries. HBI - How? Industrial Production. Today, HBI is produced in the form of briquettes at high temperature and pressure with roller presses. Alternative briquette sizes and shapes have been tested in several plants. Figure 2: HBI Briquettes with different shapes and volumes 4
Page 1 and 2: No. 11.7 HBI - Hot Briquetting of D
Page 3: Today, an increasing number of Merc
Page 7 and 8: Figure 4: Briquetting machine for D
Page 9 and 10: Figure 8: Briquettes made of produc
Page 11 and 12: HBI capacity worldwide USA Venezuel
Page 13 and 14: HBI Plants Worldwide Startup Plant
Page 15 and 16: In the meantime, an ISO committee i

Hot Briquetting of Direct Reduced - Maschinenfabrik KÃ¶ppern GmbH ...

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